The present invention relates generally to hydromechanical limited slip couplings of the type used in motor vehicle driveline applications. In particular, the present invention is directed to a differential assembly having a pair of hydraulic couplings, each having a hydraulic pump, a transfer clutch, and a fluid distribution system for distributing fluid from the pump to a first chamber for actuating the transfer clutch and to a second chamber for lubricating and cooling the transfer clutch.
Hydraulic couplings are used in various vehicular drivetrain applications to limit slip and transfer drive torque between a pair of rotary members. In all-wheel drive applications, hydraulic couplings are used to automatically control the drive torque transferred from a driven member to a non-driven member in response to speed differentiation therebetween. In limited slip applications, couplings are used in association with a differential to automatically limit slip and bias the torque distribution between a pair of rotary members. Examples of hydraulic couplings which are adaptable for such driveline applications include viscous couplings, geared traction units, and electronically-controlled friction clutches generally similar to those shown and described in commonly-owned U.S. Pat. Nos. 4,650,028, 5,148,900; 5,358,454; 5,323,871; 5,649,459; 5,704,863 and 5,779,013.
While known hydraulic couplings, including but not limited to those discussed above, have proven to be acceptable for various vehicular driveline applications, such devices are nevertheless susceptible to improvements that may enhance their performance and cost. With this in mind, a need exists to develop improved hydraulic couplings and driveline apparatuses which advance the art.